I reasonable protoss player will scout. This build cuts out a lot of zerglings and unless you can deny a probe scout it will be very transparent that you're going for a 7RR. A zerg who does not take an expansion quickly or lets at least a few lings to scout / deny scouting is very suspicious. Additionally protoss have access to the sentry and zealots will kill a roach in a 1v1 battle. They key is to force the roaches halfway up your ramp then cutting them off in half. Ideally 3 on top of your ramp and 4 below. A few stalkers should be able to hold them off.

Forging up, and dual expoing (correct me if I misread you when you said dual exp) into "quick" air is not a viable strategy.

A reliable strategy would be to hold off the initial push and securing your natural. You should be in an economic lead since he sacrificed 7 larvae early on in the game for the attack. From there the game should transfer into a standard ZvP with the protoss being slightly ahead due to a higher probe count.